Locking system especially for automobiles

ABSTRACT

A locking system for an automobile, comprises an operating key, an operating key receptacle and an associated operating unit. The operating key and the operating key receptacle have first means for transmitting a first coded operating signal from the operating key to the operating key receptacle. In addition, further second means are arranged in the operating key and in the operating key receptacle, for transmitting a second coded operating signal from the operating key receptacle to the operating key. The second operating signal cooperates with the first operating signal in a bidirectional communication in the manner of an alternating code, activation of the operating unit being made possible in the event of successful deciphering of the first transmitted operating signal.

BACKGROUND OF THE INVENTION

The invention relates to a locking system, particularly for anautomobile, including an operating key, an operating key receptacle, anoperating unit and means for transmitting coded operating signalslocated in the operating key and the operating key receptacle foractivating the operating unit upon a successful deciphering of the codedoperating signals.

Locking systems of this type serve as a safety measure against theunauthorized operation of devices equipped with them. When the lockingsystem is actuated by a user, the authorization of the latter is checkedand only the presence of the correct authorization affords theprecondition for the intended use of the device. In particular onautomobiles, such locking systems are employed as an ignition lock foran associated operating unit and/or for locking and unlocking the doors.

German Offenlungsschrift 3,436,761 discloses a locking system for anautomobile which comprises an operating key, an operating key receptacleand connecting lines from an associated operating unit. An operatingsignal transmitter having an operating signal encoder is arranged in theoperating key and an operating signal receiver having an operatingsignal decoder is arranged in the operating key receptacle. A codedoperating signal can be transmitted from the operating signaltransmitter to the operating signal receiver, the activation of theoperating unit being carried out after the successful decoding of thisoperating signal in the operating signal decoder.

It has emerged that a locking system of this type is not theft-proof. Bylistening to and/or copying the operating signal transmitted by theoperating key, it is possible to make a substitute key. By means of thissubstitute key, activation of the operating unit and consequently theftof the automobile are then possible.

In order to function, the operating key requires an energy source, whichmay be exhausted after a particular period of service. In such aninstance, the operating key is no longer operational. Activation of theoperating unit then cannot take place.

FR-A-2 674 895 describes a locking system for the doors of an automobilewhich operates by means of radio waves for data transmission. Located inthe door of the automobile is a first transmitter/receiver with anantenna. Located in the grip of an associated key is an antenna with asecond transmitter/receiver. A first code is transmitted from the firsttransmitter to the second receiver in the key. Energy is obtained fromthis signal for supplying the key and the first code is evaluated.Subsequently, a second code is transmitted from the second transmitterto the first receiver in the door of the automobile and is evaluatedthere. In the case of positive evaluation, the central locking system inthe door of the automobile is actuated.

In the case of this locking system, there in turn takes place abidirectional code transmission with simultaneous transmission of energyto the key for its operation. The range of problems already mentionedalso occur here. Further locking or security systems which operate bymeans of a bidirectional data transmission for exchanging the codes aredescribed in GB-A-2 051 442 and DE-U-93 07 176. However, a transmissionof energy for the operation of the key is not shown there.

EP-A-0 307 749 in turn discloses a data transmission device which can beused as a locking system, having two optical transmitting/receivingunits, in which device data are bidirectionally transmitted optically.After successful dialogue of the data transmission, the locking systemis actuated. In the first transmitting/receiving unit there isadditionally arranged a light transmitter for the transmission of lightenergy and in the second transmitting/receiving unit there is arranged alight receiver for converting the light energy into electrical energy.There is further located in the second transmitting/receiving unit astore for the electrical energy, for example a capacitor, so that thesecond transmitting/receiving unit is supplied with power by thistransmitted energy. The light energy is transmitted in the transmittingbreaks of the data transmission.

In the case of this locking system, the problem is that reliableoperation is not possible when there is simultaneous transmission ofenergy and data. The difficulties in the case of a system according tothe prior art lie here in the fact that, when there is simultaneoustransmission, an adequate level of energy emission can disturb the datatransmission. Therefore, the data transmission is carried out at aseparate time from the energy transmission, which increases the overalllength of time of the transmissions. As a result, the risk of operatingerrors, and consequently of adverse effects on the anti-theft security,is increased.

SUMMARY OF THE INVENTION

The object on which the invention is based is to specify a lockingsystem of the type mentioned, especially for an automobile, havingimproved theft protection and functional reliability.

This problem is achieved according to the invention by the provision ofa locking system for an automobile, comprising: an operating key; anoperating key receptacle; an operating unit associated with theoperating key receptacle; a light guide in the operating key receptacle;and electro-optical converter elements, including luminous elements andphotocells arranged in the operating key and in the operating keyreceptacle optically coupled to the light guide, for transmitting anoptical energy signal through the light guide from the operating keyreceptacle to the operating key for supplying energy for operation ofthe operating key, and for transmitting coded operating signals throughthe light guide, including a second operating signal transmitted fromthe operating key receptacle to the operating key and a first operatingsignal transmitted from the operating key to the operating keyreceptacle, wherein the second operating signal operates jointly withthe first operating signal in a bidirectional communication toconstitute an alternating code for activation of the operating unit upona successful decoding of the two transmitted operating signals.according to the invention is distinguished by the fact that the signaltransmission takes place via a light guide arranged in the operating keyreceptacle and/or the energy transmission takes place via a light guidearranged in the operating key receptacle, and that the correspondingelectrooptical converter elements located in the operating keyreceptacle are optically connected to the light guide or the lightguides.

According to a further aspect of the invention, the locking system canbe designed not only as an ignition lock for activating engineelectronics, an immobilizer or the like, but also for reliable remotecontrol of the central locking system on the automobile. Furthermore,the locking system can be connected via a bus node to a bus systemlocated in the automobile. The locking system is based on an, ifappropriate, wireless transmission of coded operating signals.

Moreover, energy transmission from the operating key receptacle to theoperating key takes place, optical energy transmission being carried outfor this purpose. This transmitted energy serves for the intendedoperation of the operating key. As a result, an additional energy storein the operating key is no longer necessary for the operation of thelatter. In the case of optical energy and signal transmission, it ispossible to arrange in the operating key receptacle a light guide rodwhich is designed for the simultaneous transmission of energy andsignals. If the operating key receptacle of the locking system isdesigned as an ignition lock, the operating key receptacle can bedesigned in such a way that the actual activation of the operating unittakes place in the usual way as a result of rotation by means of theoperating key.

The advantages achieved by the invention are, in particular, that afurther improvement in theft protection is obtained. It is not possibleto listen to the operating key via a minitransmitter. The operating keytherefore cannot, in practice, be copied, with the result thatactivation of the operating unit is impossible for unauthorized parties.

The operating key is largely maintenance-free. The supply of energy tothe operating key takes place by means of the operating key receptacle.Even when the energy store in the operating key is in fact exhausted, anintended use of the operating key is still possible. Thus, a duplicatekey can be designed, even entirely without an energy store, foractivating the operating unit with the same degree of security. Thelocking system can also be produced merely as a partial refinementwithout remotely controllable door opening, the same degree of startingsecurity being provided, in which case there is no need for theoperating key to have its own energy store.

The operating key receptacle can be of a very simple mechanical design,so that the locking system according to the invention, whilst havingincreased theft protection, can be produced at markedly lower costs thanconventional mechanical locking systems. Furthermore, the operating keyreceptacle can be integrated in a simple way into a bus system. Thisadvantageously results in a low outlay in terms of cabling, along withhigh operating reliability.

BRIEF DESCRIPTION OF THE INVENTION

Exemplary embodiments of the invention are represented in the drawingsand are described in more detail below. In the drawings:

FIG. 1 shows schematically a functional overview of the locking systemin an automobile,

FIGS. 2a and 2b show block diagrams of alternative embodiments ofelectronics for the locking system,

FIG. 3 shows a longitudinal section through an operating key, and

FIG. 4 shows a longitudinal section through an operating key receptacle.

DETAILED DESCRIPTION OF THE INVENTION

The locking system 1 shown in FIG. 1 is intended for an automobile andcomprises an operating key 2, of an operating key receptacle 3 designedas an ignition lock and connecting lines 4 to a bus node 20. Bus lines39 lead further from the bus node 20 to an associated operating unit 5.The operating unit 5 may be, for example, the electronic engine controlof the automobile, an immobilizer or the like. By means of the operatingkey 2 inserted into the operating key receptacle 3, the operating unit 5can be activated by means of corresponding bus signals transmitted viathe bus lines 39.

The bus system comprising the bus node 20 and the bus lines 39 may be,for example, the CAN bus known from automobile electronics, such as isdescribed by way of example in the literature reference Philips: CANProducts for universal fields of use, January 1992. A different bussystem can, of course, also be used equally well.

In the present case, the operating key 2 of the locking system 1 servesat the same time for the remotely controllable actuation of the centrallocking system for the doors 12 of the automobile. The remote control issupplied by an energy store 38 (see FIG. 3) located in the operating key2. Arranged in the automobile is a sensor which corresponds to theremote control in the operating key 2 and which is designed, forexample, as a roof sensor 6 having a reception range of approximately360°. This roof sensor 6 is attached to the interior mirror 7. The roofsensor 6, working in pulsed mode to minimize current, is connected tothe bus node 20 via connecting lines 8. When the roof sensor 6 receivessignals from the operating key 2, these bring about their processing bymeans of an alerting circuit located in the bus node 20. Correspondingbus signals are then transmitted via the bus lines 39 to the controlunit 9 for the central locking system. Thus, by pressing a button 10 onthe operating key 2, the central locking system can be actuated for thelocking and unlocking of the doors 12 of the automobile.

The locking system 1 can advantageously serve at the same time forlocking and unlocking the alarm system. In that case, the functions ofthe alarm system are controlled according to the control in theoperating key receptacle 3. Furthermore, a logic unit for determiningthe voltage of the energy store 38 in the operating key 2 can bearranged in the operating key receptacle 3, so that an intrusion byopening a door 12 of the automobile is detected.

The operating key 2 has, furthermore, a swing-out mechanical key 11.Arranged on the driver's side automobile door 12 is conventionalmechanical door lock 13 which can be unlocked by means of the mechanicalkey 11. An emergency opening of the automobile in the event of failureof the central locking system, for example if the energy store 38 in theoperating key 2 is empty, is thereby possible.

According to a further embodiment, the locking system 1 can also beproduced merely as a partial refinement, dispensing with remotelycontrollable actuation of the central locking system. In thisembodiment, the locking and unlocking of the automobile doors 12 takesplace in a conventional way by means of a mechanical key 11. Theoperating unit 5 is activated in the inventive way according tobidirectional communication, which is explained in more detail later, bymeans of the operating key 2 inserted in the operating key receptacle 3.In this partial refinement, at least the costs of the roof sensor 6 canbe saved, at the expense of less convenient operation.

The design of the operating key receptacle 3 as an ignition lock, asshown in FIG. 1, is in fact preferred, but the operating key receptaclecan also be designed as some other device on the automobile which can becontrolled by means of the operating key 2. Thus, the operating keyreceptacle can also be designed as a signal processing device, locatedon the automobile, for the central locking system, which can be remotelycontrollable by means of the operating key 2, and the operating unit canbe designed as a central locking system for unlocking and locking theautomobile doors 12. In this case, after successful bidirectionaltransmission of the operating signals in the manner of an alternatingcode between the operating key 2 and the signal processing device, thecentral locking system is actuated by the signal processing device forthe locking or unlocking of the automobile doors 12. The bidirectionaltransmission of the operating signals is explained in more detail below.

The more detailed design of the electronics of the central lockingsystem 1 is shown in the block diagrams of FIGS. 2a and 2b in whichcommon elements have the same reference numerals. The operating key 2has key electronics 14 comprising an integrated circuit. These keyelectronics 14 contain a first operating signal transmitter 15, whichcan be designed as an infrared transmitter having an infraredtransmitting diode 17. The key electronics 14 contain furthermore afirst operating signal encoder 16, which is connected in turn to thefirst operating signal transmitter 15. The operating key receptacle 3has a first operating signal receiver 21, designed as an infraredreceiver, with an associated infrared receiving diode 22, and a firstoperating signal decoder 23, connected to the first operating signalreceiver 21. A first coded operating signal can thereby be transmittedfrom the first operating signal transmitter 15 of the operating key 2 tothe first operating signal receiver 21 in the operating key receptacle3. Furthermore, in each case, a second operating signal receiver 24,designed as an infrared receiver, with an associated infrared receivingdiode 25, and a second operating signal decoder 26, connected thereto,are arranged in the operating key 2 and a second operating signaltransmitter 27, designed as an infrared transmitter, with an associatedinfrared transmitting diode 22, and a second operating signal encoder29, connected thereto, are arranged in the operating key receptacle 3.As a result, once again, a second coded operating signal can betransmitted from the second operating signal transmitter 27 in theoperating key receptacle 3 to the second operating signal receiver 24 inthe operating key 2. The transmission medium for the infrared signalsserving as operating signals can comprise air, but a light guidearranged in the operating key receptacle 3 is preferably used for thispurpose. To activate the operating unit 5, the second operating signalcooperates with the first operating signal in a bidirectionalcommunication 46 in the manner of an alternating code.

The function of the already mentioned remote control of the centrallocking system is also performed by the first operating signaltransmitter 15, in that, when the button 10 is actuated, saidtransmitter transmits a code, enciphered by the first operating signalencoder 16, as a third operating signal via the infrared transmittingdiode 17. One or more infrared receiving diodes 18 having a connectedthird operating signal receiver 19 are located in the roof sensor 6. Thethird operating signal is fed via the connecting lines 8 to the bus node20 for evaluation and further processing.

In FIG. 2A, it can be seen, as a further embodiment, that the bus node20 can advantageously be arranged in the operating key receptacle 3. Theroof sensor 6 is, in that case, connected to the bus node 20 via theoperating key receptacle 3. The first operating signal decoder 23 can bea separate circuit in the operating key receptacle 3, the code,deciphered by the first operating signal decoder 23, being transmittedas a binary signal to the bus node 20. It is also possible, however, tointegrate the function of the operating signal decoder into the bus node20, so that the operating signal received by the first operating signalreceiver 21 is transmitted directly as a coded signal to the bus node20. Alternatively, it is possible, furthermore, to transmit the receivedinfrared signals by means of a light guide to the bus node 20 and onlythere convert them into electrical signals for further processing.

As soon as the operating key 2 is inserted into the operating keyreceptacle 3, a switch 30 in the operating key receptacle 3 is actuatedby the operating key 2. By means of the switch 30, an optical energytransmission 47 between the operating key receptacle 3 and the operatingkey 2 is then switched on. The key electronics 14 are consequently thensupplied with energy by the operating key receptacle 3, so that anenergy store 38 present in the operating key 2 is required only duringthe actuation of the remote control for central locking, which takesplace outside the operating key receptacle 3. As a result, the energystore 38 (FIG. 5) has a very long service life, so that it is veryseldom necessary to exchange the energy store 38. If, instead of abattery, an accumulator is used for the energy store 38, this can berecharged, even while the operating key 2 is located in the operatingkey receptacle 3, thereby making it unnecessary to exchange the energystore 38.

To increase the operating reliability, the optical energy transmission47 takes place, as shown in FIG. 2a, by means of light beams, as orinfrared beams is particularly preferred, as shown in FIG. 2b in afurther embodiment of the locking system. When the switch 30 is actuatedby the operating key 2 inserted into the operating key receptacle 3, theenergy transmission electronics 32, again supplied by the on-board powersupply feed line 33, supplies a luminous element 48 which emits, forexample, infrared beams. These infrared beams are transmitted to acorresponding photocell 49 in the operating key 2, specifically, as isparticularly preferred, via a light guide. In this photocell 49, theinfrared beams are then converted again into an electric voltage. Theenergy transmitted optically by means of the electrooptical convertorelements, namely the luminous element 48 and the photocell 49, servesonce again for operating the key electronics 14.

As can be further inferred from FIG. 2A, the key electronics 14 containa data memory 35 which may be, for example, an EEPROM memory. A uniqueidentification for the respective automobile is filed as an individualidentification in this data memory 35. This individual identificationmay be, for example, a unique number issued by the automobilemanufacturer. The same individual identification is likewise stored in adata memory 37 in the operating key receptacle 3. The operating signalencoders 16, 29 and operating signal decoders 23, 26 work according to afixed algorithm. The algorithm can, if appropriate, be filed in the datamemory 35, 37 or else be obtained by means of a corresponding electroniccircuit. Furthermore, a random number generator 36 is also located inthe operating key receptacle 3.

To activate the operating unit 5, after the operating key 2 is insertedinto the operating key receptacle 3 and the energy transmission 47 isswitched on, a once-only identifying of the individual identification iscarried out by means of the bidirectional communication 46 between thetwo operating signals in the manner of an alternating code. Thisbidirectional communication 46 works in detail as follows.

First of all, a random number is determined as an identification numberby means of the random number generator 36 and is stored in the datamemory 37 of the operating key receptacle 3. A code is formed from thisidentification number in the second operating signal encoder 29 of theoperating key receptacle 3 by means of the fixed algorithm and istransmitted as the second operating signal to the operating key 2 bymeans of the second operating signal transmitter 27. This secondoperating signal, received by the operating key 2 by means of the secondoperating signal receiver 24, is deciphered into a transmittedidentification number by means of the second operating signal decoder 26with the aid of the algorithm. After deciphering has taken place, thetransmitted identification number and the individual identificationstored in the data memory 35 of the operating key 2 are then used toform a first operating signal in the first operating signal encoder 16of the operating key 2 with the aid of the fixed algorithm. At the sametime, the transmitted identification number is stored in the data memory35. If, in the expanded refinement stage, the operating key 2 has remotecontrol for door opening, an additional counter, which counts the numberof door openings, is set to zero, and this count is stored in the datamemory 35. The first operating signal is subsequently transmitted to thefirst operating signal receiver 21 in the operating key receptacle 3.Thereafter, the first operating signal is deciphered in the firstoperating signal decoder 23 of the operating key receptacle 3 accordingto the fixed algorithm, thus resulting in a determined identificationnumber and a determined individual identification. A comparison of thedetermined individual identification and determined identificationnumber with the individual identification and identification numberstored in the data memory 37 is subsequently carried out. If thiscomparison has a positive result, that is to say if the individualidentification and identification number are correct, the activation ofthe operating unit 5 is cleared by the operating key receptacle 3 viathe bus node 20, otherwise activation cannot take place. The count forthe door opening filed in the data memory 37, if present according tothe expanded refinement stage, is likewise set to zero if there is apositive comparison in terms of individual identification andidentification number.

To ensure less complication, for the remote control of the centrallocking system there is only unidirectional signal transmission from theoperating key 2 to the roof sensor 6, although, even there, abidirectional communication which is secure in terms of theft protectionis possible in a similar way to that between the operating key 2 and theoperating key receptacle 3. The unidirectional signal transmission worksin detail as follows.

When the button 10 is actuated, in the operating key 2 a third operatingsignal is formed from the individual identification stored in the datamemory 35, the transmitted identification number, determined during thelast activation in the random number generator 36 of the operating keyreceptacle 3, and a counter, incremented by one, which counts the numberof door openings since the last activation of the automobile, by meansof a fixed algorithm in the first operating signal encoder 16, and saidthird operating signal is transmitted. At the same time, the incrementedcount is filed in the data memory 35 of the operating key 2. The thirdoperating signal received via the roof sensor 6 is transmitted to thebus node 20 in the operating key receptacle 3 and is deciphered there ina decoder, assigned to the roof sensor 6, by means of the identificationnumber stored in the data memory 37 and by means of the fixed algorithm.This decoder can be the first operating signal decoder 23 alreadylocated in the operating key receptacle 3. The result of the decipheringgives a determined individual identification and a determined count. Thedetermined individual identification is compared with the individualidentification stored in the memory 37 and, if they are identical, thereis a further check as to whether the determined count is higher than orequal to the count for the number of door openings, the latter countbeing stored in the data memory 37 of the operating key receptacle 3. Ifthis condition is likewise satisfied, unlocking or locking is triggeredon the control unit 9 of the central locking system. At the same time,the count in the data memory 37 of the operating key receptacle 3 isreplaced by the determined count.

A comparison of the count for the number of door openings in theoperating key 2 with the count in the operating key receptacle 3 ensuresthat an unauthorized user can open the automobile only once by means ofan operating key copied by listening to the transmitted third operatingsignal. As soon as the authorized user actuates the door opening afurther time, the count changes, without activation of the automobilebeing necessary, and a further opening by means of the copied key is nolonger possible. For a further increase in theft protection, the twoalgorithms for actuating the operating unit 5 and the control unit 9 forthe central locking system can be different and/or changed at specifictime intervals.

In a preferred embodiment of the invention, the transmission of thefirst and second operating signal in bidirectional communication and ofthe third operating signal in unidirectional communication takes place,as described, as an infrared signal.

After the activation of the operating unit 5 is cleared by the bus node20, actuation for unlocking a steering wheel lock known per se, notshown in more detail, can be simultaneously triggered. The actuation ofthe steering wheel lock can take place by means of an electromagnet. Theactivation of the operating unit 5 is thereafter carried out via the busnode 20 by means of a further signal triggered by the user.

The more detailed design of the operating key 2 and of the operating keyreceptacle 3 can be seen in FIGS. 3 and 4. As shown in FIG. 3, theoperating key 2 has a housing 40, the rear part of which contains aprinted circuit board 41. The key electronics 14, designed as anintegrated circuit, are located on the printed circuit board 41. Thefront part of the housing 40 is designed as a type of plug 42 forinsertion into the operating key receptacle 3 and contains orifices, inwhich the infrared transmitting diode 17 of the first operating signaltransmitter 15 and the infrared receiving diode 25 of the secondoperating signal receiver 24 are arranged with connection to the printedcircuit board 41. Furthermore, the photocell 49 is also located in theplug. Finally, the housing 40 also contains the schematically indicatedenergy store 38 for the remote control of the central locking system.

As shown in FIG. 4, the operating key receptacle 3 comprises a housing43 which terminates in a type of plug socket 44 for receiving the plug42 on the operating key 2. The light guides serving for optical signaland energy transmission are designed as a common light guide rod 50,which is located in the housing 43. The light guide rod 50 comprises alight guide 53, located in the middle, for optical energy transmission47 and a further light guide 54 for optical signal transmission, whichannularly surrounds the middle light guide 53, so that the two lightguides 53, 54 form a common solid rod. The two light guides 53, 54 areseparated by a non-photoconductive layer 55 lying between them. One endof the light guide rod 50 is arranged in the immediate vicinity of theplug socket 44. The light guide rod 50 leads from the plug socket 44 asfar as a printed circuit board 51 located in the housing 43 of theoperating key receptacle 3, there being arranged at the second end ofthe light guide rod 50 the electrooptical convertor elements withoptical connection to the light guide rod 50 on the printed circuitboard 51, namely the infrared receiving diode 22 of the first operatingsignal receiver 21 and the infrared transmitting diode 28, not visiblein FIG. 4, of the second operating signal transmitter 27 as well as theluminous element 48. When the operating key 2 is inserted into theoperating key receptacle 3 at the orifice 52 of the plug socket 44, theelectrooptical convertor elements in the operating key 2, namely theinfrared transmitting diode 17, the infrared receiving diode 25 and thephotocell 49, are optically connected to the first end of the lightguide rod 50. Consequently, the infrared transmitting diode 17 of theoperating key 2 and the infrared receiving diode 22 of the operating keyreceptacle 3 as well as the infrared receiving diode 25 of the operatingkey 2 and the infrared transmitting diode 28 of the operating keyreceptacle 3 are optically coupled via the light guide 54 of the lightguide rod 50. Furthermore, optical coupling takes place by means of thelight guide 53 of the light guide rod 50 between the luminous element 48of the operating key receptacle 3 and the photocell 49 of the operatingkey 2 for energy transmission 47.

So that the actual activation is designed as the user is accustomed forthe operation of starting the automobile by means of a conventionalignition lock, the plug socket 44 in the operating key receptacle 3 ispreferably made rotatable. An elastically coupled rotary sleeve 45 inthe operating key receptacle 3 is operatively connected to the plugsocket 44. To initiate the activation after a successful transmission ofthe two operating signals according to the bidirectional communication46, the rotary sleeve 45 is then first unlocked by moving a stop pin 57of an electromagnetic blocking device 56 out of engagement with therotary sleeve 45. The user can then, as in a conventional ignition lock2 too, now rotate the operating key 2 together with the plug socket 44and the rotary sleeve 45. In this case, switching signals are generatedin specific rotary positions of the rotary sleeve 45 by means of adevice. This device for generating the switching signals comprisesmechanical, electronic, optical, optoelectronic or such like switchingelements, not shown further, which are located in the housing 43 andwhich are actuated by the rotary sleeve 45. These switching signals aretransmitted to the bus node 20 and bring about the clearance of theparking light, specific parts of the energy supply, for example for theautomobile radio, etc. Finally, one of these switching signals servesfor activating the operating unit 5, that is to say, for example, forstarting the engine of the automobile.

In order to terminate the operation of the operating unit 5, theoperating key 2, together with the plug socket 44 and the rotary sleeve45, is rotated back again. In this case, the switching signals arechanged by the device for generating switching signals, that is to saythe corresponding switching elements are switched off again. The changedswitching signals are transmitted via the bus node 20 for deactivatingthe operating unit 5. When the operating key 2 is withdrawn from theoperating key receptacle 3, at the same time a locking of the steeringwheel by means of a mechanical steering wheel lock can take place, andlocking can be brought about by the switching signal of the switch 30.

The data memory 35 in the operating key 2 can also be utilized forfurther functions, for example for the storage of service data, userdata and the like. In particular, permanent data transmission from theoperating key receptacle 3 to the operating key 2 can take place whilethe automobile is traveling by means of the second operating signaltransmitter 27 and the second operating signal receiver 24. Travel datacan thereby be stored in the data memory 35 in the manner of anelectronic logbook.

The invention is not restricted to the exemplary embodiments describedand represented. On the contrary, it also embraces all developmentswithin the scope of the inventive idea which are open to a personskilled in the art. Thus, a locking system of this type can not only beemployed on automobiles, but also be used on doors, for example inbuilding technology.

We claim:
 1. A locking system for an automobile, comprising:an operatingkey; an operating key receptacle; an operating unit associated with theoperating key receptacle; a light guide in the operating key receptacle;and electro-optical converter elements, including luminous elements andphotocells arranged in the operating key and in the operating keyreceptacle, optically coupled to the light guide, for transmitting anoptical energy signal through the light guide from the operating keyreceptacle to the operating key for supplying energy for operation ofthe operating key, and for transmitting coded operating signals throughthe light guide, including a second operating signal transmitted fromthe operating key receptacle to the operating key and a first operatingsignal transmitted from the operating key to the operating keyreceptacle, wherein the second operating signal operates jointly withthe first operating signal in a bidirectional communication toconstitute an alternating code for activation of the operating unit upona successful decoding of the two transmitted operating signals.
 2. Thelocking system according to claim 1, wherein the light guide comprises acommon light guide including a first light guide for transmitting theoptical energy signal and second light guide optically separated fromthe first light guide for transmitting the coded operating signals. 3.The locking system according to claim 2, wherein the second light guideannularly surrounds the first light guide and further including anon-photoconductive layer disposed between the first and second lightguides.
 4. The locking system according to claim 1, wherein theoperating key and the operating key receptacle contain first and seconddata memories, respectively, each for storing an individualidentification number comprising a unique number, the operating keyreceptacle includes a random number generator for generating a randomnumber as the unique number and means for enciphering the code of thesecond operating signal with the random number as the identificationnumber with the use of an algorithm; and the operating key includesmeans for enciphering the code of the first operating signal with theidentification number also with the use of an algorithm.
 5. The lockingsystem according to claim 4, and further including: a sensor with areception range of about 360° arranged on the automobile for controllinga central locking system for doors of the automobile; and a decoderassigned to the sensor; wherein the electro-optical converter elementsin the operating key are for transmitting a third operating signalhaving an enciphered code and the operating key further includes acontrollable switch for initiating a unidirectional transmission of thethird operating signal which when sensed by the sensor and deciphered bythe decoder assigned to the sensor, allows locking and unlocking of thecentral locking system.
 6. The locking system according to claim 5,wherein the enciphered code of the third operating signal contains theidentification number determined during a last activation of theoperating unit and stored in the data memory of the operating key; andthe operating key includes a counter and means for incrementing thecounter by one each time the central locking system is actuated andstoring the count in the data memory of the operating key, theenciphered code of the third operating signal additionally containingthe stored count of the counter since the last activation of the centrallocking system.
 7. The locking system according to claim 4, and furtherincluding: a sensor with a reception range of about 360° arranged on theautomobile for controlling a central locking system for doors of theautomobile; and a decoder assigned to the sensor; wherein theelectro-optical converter elements in the operating key are fortransmitting a third operating signal having an enciphered code and theoperating key further includes a controllable switch for initiating aunidirectional transmission of the third operating signal which whensensed by the sensor and deciphered by the decoder assigned to thesensor, allows locking and unlocking of the central locking system; thelocking system further including a bus node for coupling the at leastone switching signal for activating the operating unit and meansconnecting the sensor to the bus node.
 8. The locking system accordingto claim 7, wherein the connecting means includes another light guidecoupling the sensor to the bus node.
 9. The locking system according toclaim 4, wherein, with the operating key inserted in the operating keyreceptacle, permanent data transmission between the operating keyreceptacle and the operating key takes place while the operating unit isin operation, and the first data memory in the operating key stores datagenerated during operation of the operating unit.
 10. The locking systemaccording to claim 1, wherein the operating key receptacle comprises anignition lock of the automobile into which the operating key isinserted, and the operating unit comprises one of engine electronics ofthe automobile and an immobilizer.
 11. The locking system according toclaim 1, wherein the operating key receptacle comprises an ignition lockincluding a rotatably arranged plug socket for receiving the operatingkey; the light guide comprises a light guide rod arranged on the plugsocket in the operating key receptacle so that when the operating key isinserted into the operating key receptacle, one end of the light guiderod makes an optical coupling with the electro-optical convertorelements in the operating key, and another end of the light guide rod isoptically coupled to corresponding electro-optical convertor elementsmounted in the operating key receptacle.
 12. The locking systemaccording to claim 11, wherein the operating key receptacle furtherincludes: a rotary sleeve elastically coupled to the plug socket forrotational movement; a blocking device lockingly engaged with the rotarysleeve and being responsive to a successful transmission of theoperating signals between the operating key and the operating keyreceptacle for unlocking the blocking device to allow rotationalmovement of the rotary sleeve; and a switching device for generatingswitching signals in dependence on a rotary position of the rotarysleeve, at least one of the switching signals being for activating theoperating unit.
 13. The locking system according to claim 12, andfurther including a bus node for coupling the at least one switchingsignal for activating the operating unit.
 14. The locking systemaccording to claim 13, wherein the bus node comprises a CAN node. 15.The locking system according to claim 1, wherein the operating keyincludes a swing-out mechanical key for emergency opening of at leastone mechanical door lock of a door of the automobile.
 16. The lockingsystem according to claim 1, wherein insertion of the operating key inthe operating key receptacle switches on a transmission of the opticalenergy signal.